Submission #700200

#	Time	Username	Problem	Language	Result	Execution time	Memory
700200		mnbvcxz123	Race (IOI11_race)	C++17	0 / 100	3029 ms	4948 KiB

race

#include<bits/stdc++.h>
#include "race.h"
using namespace std;
using ll=long long;
using ar=array<int,2>;

int n,k,res=1e6;
vector<ar>g[200000];

int sz[200000];
bool used[200000];
map<ll,int>mp;

void siz(int v, int e){
        sz[v]=1;
        for(const auto&[i,w]:g[v])
                if(i!=e and !used[i])
                        siz(i,v),sz[v]+=sz[i];
}

int get(int v, int e, int des){
        for(const auto&[i,w]:g[v])
                if(i!=e and !used[i] and sz[i]>des)
                        return get(i,v,des);
        return v;
}

void help(int v, int e, ll km, int d, bool fill){
        if(km>k) return;
        if(fill){
                if(mp[km]==0)
                        mp[km]=d;
                else
                        mp[k-km]=min(mp[k-km],d);
        }
        else{
                if(km==k)
                        res=min(res,d);
                else if(mp[k-km]!=0)
                        res=min(res,d+mp[k-km]);
        }
        for(const auto&[i,w]:g[v])
                if(!used[i])
                        help(i,v,km+w,d+1,fill);
}

void decomp(int v=0){
        siz(v,-1);
        int c=get(v,-1,sz[v]>>1);
        used[c]=1;
        mp[c]=0;
        for(const auto&[i,w]:g[c])
                if(!used[i]){
                        help(i,c,w,1,0);
                        help(i,c,w,1,1);
                }
        mp.clear();
        for(const auto&[i,w]:g[c])
                if(!used[i])
                        decomp(i);
}

int best_path(int N, int K, int H[][2],int L[]){
        n=N;
        k=K;
        for(int i=0;i<n-1;++i){
                g[H[i][0]].push_back({H[i][1],L[i]});
                g[H[i][1]].push_back({H[i][0],L[i]});
        }
        decomp();
        if(res==1e6) return -1;
        return res;
}

• Subtask 1: 0 / 9
• Subtask 2: 0 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57